Mechanics of a septin cortex (MEP)

What and Why

The shape of eukaryotic cells is very important for their function: muscle cells are elongated to achieve contraction, and cells in your intestines have many microvilli for nutrient uptake. Since the cell membrane is very thin and soft, shaping of the cell is achieved by a stiffer structure supporting the membrane: the actin cortex. This cortex is a network of actin filaments that are cross-linked and bound to the membrane.

Although actin is the main component of this cortex, there are many other proteins that cross-link the actin filaments and that stick the cortex to the membrane. A rather unknown component is septin. Septins are proteins that can form higher order structures such as filaments and bundles. Septins can act as an actin-membrane linker, but we have shown before that septins can form a protein meshwork on membranes in absence of actin by themselves. The role of such a ‘septin cortex’ in the mechanical response of the eukaryotic cell membrane has to date not been investigated.

The Project

In this project, you will investigate how septins influence membrane mechanics using a bottom-up reconstitution approach. You will encapsulate septins inside artificial membrane containers using a semi-microfluidic technique which is already operational in our group. You will tune septin-membrane interactions to create a septin cortex. Then, you will measure and compare mechanical properties of artificial membranes with and without a septin cortex.
This project gives you the opportunity to learn how to work with purified proteins, state of the art microscopy and single-cell micromanipulation techniques.


You participate in a Bachelor or Master study in physics, chemistry, biology or related.


Gerard Castro-Linares ( and Lennard van Buren (

Group leader: Gijsje Koenderink (

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